NuForce Icon uDAC-2 Headphone Amp/DAC Review

I have mentioned in the last few reviews that I am now reviewing headphones using the NuForce uDAC-2 USB amp/DAC plugged into my new iMac, when I am not using my iPod. There’s a really good reason for this. The iMac audio output sounds like … well, let’s just say it sounds bad. Really, really bad. It finally dawned on me why anyone would spend hard-earned money on a decent pair of headphones or earphones only to have the experience ruined by the iMac’s lousy internal DAC. No one should spend a dime on new headphones if all they are going to do is plug them directly into the audio-out port on the iMac. After putting up with distortion on some of my more challenging tracks in iTunes, I finally gave up. I just plugged phones into my iPod Classic or iPhone if I wanted decent audio.

Then I saw the uDAC-2. I knew that there were other headphone amps out there, many models by many brands in every price range. But I liked the NuForce name as I had reviewed one of their earphones in the past and liked their quality and price. So I was curious if the uDAC-2 could help clean up this aural mess from my computer.

First, let me explain what exactly a DAC and amplifier do. The amp part is just what it says. It amplifies the signal and allows you to connect headphones that may be too power hungry for your device, which can rob you of clarity and volume. The digital audio converter (DAC) is a bit more tricky to explain. Basically a DAC reroutes the digital signal coming from your device and converts it to analog – the music you hear in your ears. So when you plug your headphones or earphones into the DAC instead of your computer, the signal is now cleaner, clearer, and more robust. However, sometimes DACs and amps are not that important, especially if you are using low cost earphones that don’t require much power or if you device already has a decent DAC built in.

The DAC in my iMac is nowhere near as good as the one in my iPod. So I decided to bypass it and connect through the uDAC-2. I do not regret it. We’ll get into specific improvements later, but I want to explain the setup. The uDAC-2 is an improvement over their original uDAC in almost every way. The uDAC-2 uses no separate power supply or batteries. It gets all of its power from a single USB connection. Because it is USB, there is a direct digital connection until the signal reaches your headphones or connected speaker through its miniplug port or standard RCA audio output. There is also a coaxial RCA digital output included.

The uDAC-2 measures 2.7 in. X 1.5 in. X .8 in. That is unbelievably small by any standard. Even though it’s designed to use with a laptop, trust me, it works just as well on a desktop iMac. It is not made to use with an iPod or iPhone (NuForce makes the Icon Mobile amp for that). This thing is so small and light, the USB cord alone can easily slide it around on your desk, sometimes annoyingly so. Its lack of weight just won’t hold it in place. I may have to get some velcro tape to correct this.

Even though I am using the uDAC-2 for headphones and earphones, I discovered that it also improved the sound of my monsterous Audioengine 5 speakers substantially. As I was writing part of this review, I had iTunes on shuffle and an old song, “Moonshine,” by Shawn Phillips came on. I’ve always liked Phillips 70s folk-rock, but I was hearing subtle piano coming out of the right speaker I’d never really noticed before. I was not expecting this. The pre-amp on the uDAC-2 fits well with the A5s built in amplifier. Here I was using this tiny DAC to do its thing on some really hefty self-amplified speakers and I was getting this kind of improvement. There was a soundstage to the music that just didn’t exist before. I was stunned.

But back to the headphones…

I want to point out two specific examples where the uDAC-2 absolutely proves its worth. This is detailed, but here are two concrete examples where a DAC/amp combo unit can raise the bar on audio expectations. These examples are not from mainstream albums but they do help explain the capabilities of the uDAC-2. The first example is the song, Water Shows The Hidden Heart” by Enya from her “Amaratine” album. At 1:40 minutes into the song, Enya’s vocals hit higher notes that have always distorted a bit before. I thought it was just bad mastering, but it wasn’t. The uDAC-2 took care of that. The same thing happened in the second example. “Liturgy of St. John Chrysostom, Op. 41 – Hymn of the Cherubim” by Tchaikovsky from “Sacred Treasures” features Russian choral music that will give you goosebumps. At 2:39 minutes into the music, what sounds like angels kicks in and as before, distortion would kick in also. Not anymore. The sheer beauty of the voices shine through like sunlight through stained glass.

Other somewhat less dramatic improvements can be found. The re-remastered “Hallelujah” from Jeff Buckley’s “So Real: Songs From Jeff Buckley” now has its original dynamics restored (that’s why it’s re-remastered). The uDAC-2 exploits this improvement. Now, Buckley’s quiet pain comes through in heartbreaking clarity. Leonard Cohen may have written this song, but Buckley made it his own.

“FYT/Fond Affections” from the first This Mortal Coil album begins with a mounting cadence and slowly builds to a climactic growl that – with headphones – could give you nightmares. This is creepy stuff made even more creepy run through the uDAC-2.

The musicality of the uDAC-2 is too impressive to ignore. The fact that NuForce could get this kind of improvement from a package this small continues to impress me. From now on, I will test headphones and earphones through a DAC/amp.

While the uDAC-2 comes with specs any audio geek would love, it really comes down to the sound quality. Just ask yourself: With the uDAC-2, is the audio improved? Yes. Is it richer? Yes. Is it less distorted? Yes. Is it all worth it? Heck, yes.

Good write-up! Thanks for sharing! I have a question or two about your stock iMac setup, as I find myself in the same boat. I put the NuForce icon 2 through its paces with a bunch of 16bit/44kHz and 24bit/96kHz content, and while it does sound rich and fulfilling, I can’t honestly say that it sounds much different than the iMac’s native headphone port. I’ve just never noticed any of the distortion you talk about here. Did you check the bit depth and resolution for the on-board DAC to make sure its set the same as the NuForce?

Only reason I ask is that I’m having a bit of buyer’s remorse, and I’m wondering if I shouldn’t just return the NuForce. I mean, how much more or better technology could they pack into a device smaller than a pack of smokes that would be an improvement on the built-in amp? Especially when you consider both still use switching power supplies.

Perhaps i should also mention that this is a brand new, 2013 27″ iMac. Thoughts?

Brett,
I can’t speak about the new iMac. Mine is a couple of generations old… the last of the 24″ model. All I can say is that the on-board DAC in my machine is terrible – and this is from an urepentant Apple fanboy. I don’t hear distortion that much, but there is most definitely distortion in those places on the songs I mentioned specifically.

Here is what I recommend: Use it as long as you can (many days) and then disconnect it and listen to the same songs. I’ve said in other reviews, it’s not an OMG device, but once you get used to it, removing it can be unpleasant.

I don’t know what my iMac DAC measurements are. I try to avoid getting that deep in my reviews because that’s not our core audience. Sites like head-fi.org are wonderful resources for that information.

That said, if you hear no audible difference with or without the DAC, then it is a waste of money to you. I believe in trusting your hearing and disregarding the measurements. Your iMac DAC may be better than mine. I hope so. It can’t be worse!

Hi, Great review. Thanks.
I am new to the audiophile world I am not there yet, but sure can appreciate great sounding music. Currently, I bought this DAC and hooked it to a Bose companion series II speaker system. I am aware that the DAC is meant for headphones. But I own those speakers for two years. As for the DAC, I love it. I am playing music from CDs and FLAC files now ( I really wish I could buy FLAC seamlessly like mp3 files. Anyway). I am now planning to get the AudioEngine A5+ (if possible) or at least the A2 speakers. Would that be a right combination? Or buy the Sennheiser HD800 headphones. I just want to know if the investment is right, after all any suggestions?

Aras,
I can’t help you decide whether to get headphones or speakers, because they are so different. It depends on your wants and needs. If you go for speakers, the Audioengine 5+ are wonderful and POWERFUL. The DAC will improve them, but I think it will be subtle. I reviewed the A5+ here: http://the-gadgeteer.com/2013/03/10/audioengine-a5-speaker-review/

I have not heard the A2 so I can’t speak on those, although I would suspect thay are similar to the A5+ but not as powerful.

I also haven’t heard the Senn 800, but have read many great things about them. I would love to review them, so who knows?

Nice write-up and exactly in accord with my own experience. I have this DAC hooked up to my Mac Pro. It makes a huge difference, especially with the lossless tracks ripped from my CDs. I liked it enough to treat myself to the NuForce Air DAC, which connects my computer(s) with my (elderly, analog-only) NAD 3400.